1. Field of the Invention
The present invention relates to a buffered crossbar switch for inter-connection between multiple modules in a communication system.
2. Description of the Related Art
A crossbar switch (also known as a “crosspoint switch” or a “matrix switch”) inter-connects a plurality of input ports and output ports to each other. A crossbar switch having P inputs and Q outputs has a switch fabric matrix with P×Q crosspoints where connections between input ports and output ports are made. Thus, packets arriving at one of the input ports might be routed to one or more specified output ports. For example, a packet might be routed to just a single specified output port (unicast), routed to all output ports (broadcast), or routed to multiple specified output ports (multicast).
Bufferless crossbar switches are frequently used in multi-processor computer systems to link processors with other resources, such as memory or other subsystems, or with internet switches or other high-performance communication networks. However, bufferless crossbar switches generally require switch fabric speedup, meaning that the internal data rate of the switch must be higher than the data rate of the link. These crossbar switches typically require high-complexity centrally-controlled scheduling algorithms to achieve 100% throughput, such as the Parallel Iterative Matching (PIM) and iSLIP algorithms.
In a buffered crossbar switch, buffers are included in the crossbar switch to temporarily store packets that cannot be routed to a specified output port instantly (i.e., blocked packets). For example, buffers might be provided for each input port, for each output port, for each crosspoint connection of the crossbar switch, or some combination thereof. Centrally-controlled scheduling algorithms might be employed to allow the input and output data streams to efficiently access the switch fabric.